Pediatric offices may choose to serve as an alternate venue for providing influenza immunization for parents and other care providers of children. Medical liability issues and medical record documentation requirements need to be considered before a pediatrician begins immunizing adults in the office. learn more at: www.aap.org/immunizations

The composition of U.S. flu vaccines is reviewed annually and updated to match circulating flu viruses. Flu vaccines protect against the three or four viruses that research suggests will be most common.

All influenza vaccines licensed in the United States will contain components derived from influenza viruses antigenically similar to those recommended by FDA. Both trivalent and quadrivalent influenza vaccines will be available in the United States. The 2018–19 U.S. influenza vaccines will contain hemagglutinin derived from the following:

an A/Michigan/45/2015 (H1N1)pdm09–like virus,

an A/Singapore/INFIMH-16-0019/2016 (H3N2)–like virus, and

a B/Colorado/06/2017–like virus (Victoria lineage).

The 2018–19 U.S. quadrivalent vaccines will contain the same three antigens and an additional influenza B virus component, a B/Phuket/3073/2013–like virus (Yamagata lineage). Compared with the 2017–18 season, the composition for 2018–19 represents changes in the A(H3N2) and B (Victoria) components of both the trivalent and quadrivalent vaccines.

These vaccine recommendations were based on several factors, including global influenza virologic and epidemiologic surveillance, genetic and antigenic characterization, human serology studies, antiviral susceptibility, and the availability of candidate influenza viruses.

Trivalent flu vaccines protect against two influenza A viruses and one influenza B virus. The following trivalent flu vaccines are available:

Standard-dose trivalent shots (IIV3) that are manufactured using virus grown in eggs. Different flu shots are approved for different age groups. Most flu shots are given in the arm (muscle) with a needle. One trivalent vaccine formulation can be given with a jet injector, for persons aged 18 through 64 years.

A trivalent flu shot made with adjuvant (an ingredient of a vaccine that helps create a stronger immune response in the patient’s body), approved for people 65 years of age and older (new this season).

Quadrivalent flu vaccines protect against two influenza A viruses and two influenza B viruses. The following quadrivalent flu vaccines are available:

An intradermal quadrivalent flu shot, which is injected into the skin instead of the muscle and uses a much smaller needle than the regular flu shot. It is approved for people 18 through 64 years of age.

A quadrivalent flu shot containing virus grown in cell culture, which is approved for people 4 years of age and older.

Influenza Vaccine Safety

Influenza vaccines are continually monitored for safety and efficacy. While influenza vaccines have proven to be very safe, some people should not be vaccinated, or should speak to the doctor before getting vaccination.

People who can't get the flu shot:

Children younger than 6 months are too young to get a flu shot

People with severe, life-threatening allergies to flu vaccine or any ingredient in the vaccine. This might include gelatin, antibiotics, or other ingredients.

Note: There are certain flu shots that have different age indications. For example people younger than 65 years of age should not get the high-dose flu shot and people who are younger than 18 years old or older than 64 years old should not get the intradermal flu shot.

People who should talk to their doctor before getting the flu shot:

If you have an allergy to eggs or any of the ingredients in the vaccine. Talk to your doctor about your allergy.

If you ever had Guillain-Barré Syndrome (a severe paralyzing illness, also called GBS). Some people with a history of GBS should not get this vaccine. Talk to your doctor about your GBS history.

Information for Pregnant Women

Influenza is more likely to cause severe illness in pregnant women than in women who are not pregnant. Changes in the immune system, heart, and lungs during pregnancy make pregnant women more prone to severe illness from influenza as well as hospitalizations and even death. Pregnant women with influenza also have a greater chance for serious problems for their unborn babies, including premature labor and delivery. Because vaccinating against influenza before the season begins is critical, and because predicting exactly when the season will begin is impossible, routine influenza vaccination is recommended for all women who are or will be pregnant (in any trimester) during influenza season, which in the United States is usually early October through late March.

Neither CDC nor ACOG recommend one type of flu vaccine. All influenza vaccines available are recommended for use in pregnant women, with the exception of the live intranasal vaccine.

Safety Information for Pregnant Women

The seasonal flu shot has been given safely to millions of pregnant women over many years. Flu shots have not been shown to cause harm to pregnant women or their babies. CDC and FDA conduct ongoing monitoring of the safety of seasonal influenza and other vaccines licensed for use in the United States, in cooperation with state and local health departments, health care providers, and other partners. Monitoring the safety of seasonal flu vaccine in pregnant women is part of this effort.

There have been no reports of any adverse outcomes in pregnant women or their infants. Thimerosal, a mercury-containing preservative used in multidose vials, has not been shown to cause any adverse effects except for occasional local skin reactions. There is no scientific evidence that thimerosal-containing vaccines cause adverse effects in children born to women who received vaccines with thimerosal. Hence, ACIP does not indicate a preference for thimerosal-containing or thimerosal-free vaccines for any group, including pregnant women (Committee Opinion #732).

All flu vaccines are either pregnancy category B or C. These are categories assigned by the FDA. Pregnancy Category B means that tests in animals have failed to demonstrate adverse effects on the fetus, however sufficient testing in pregnant women has not been conducted. Pregnancy Category C means that animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women.

Despite these categories influenza vaccines are recommended by CDC because millions of doses have been given to pregnant women with no adverse events occurring.

Monitoring the Safety of Influenza Vaccination during Pregnancy

In order to monitor the safety of influenza vaccination during pregnancy, influenza vaccine manufacturers have developed pregnancy registries. ACOG encourages providers who administer flu vaccine to pregnant patients to participate in these registries. Please see the below links to information about each manufacturer's pregnancy registry.*

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